1, 1-bis(3, 5-dialkyl-4-hydroxyphenyl) methanes



United States Patent 1,1-BIS (3,5-DIALKYL-4 -HYDROXYPHENYL) METHANES Thomas H. Coflield, Birmingham, and Allen H. Filbey, Walled Lake, Mich., assignors to Ethyl Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed Sept. 23, 1955, Ser. No. 536,315

'3 Claims. (Cl. 260-619) This invention relates to novel chemical compounds having utility in the chemical arts.

In particular, this invention relates to novel 1,1-bis- (3,5-dialkyl-4-hydroxyphenyl)methanes which are eminently suited for use as antioxidants.

Among objects of this invention is that of providing new chemical compounds useful for the above and other purposes. Another object is to provide a hydrocarbon oil normally tending to deteriorate in the presence of oxygen containing these new compounds in amount sufficient to inhibit this deterioration. Another object is to provide lubricating oil normally tending to deteriorate in the presence of oxygen containing in amount sufiicient to inhibit such deterioration a small antioxidant quantity of novel and highly effective antioxidants. Still another object is to provide turbine and other industrial oils stabilized against oxidative deterioration by the presence therein of a small antioxidant quantity of novel and highly effective antioxidants. Other objects will be apparent from the ensuing description.

The above and other objects of this invention are accomplished by providing as new compositions of matter 1,l-bis-(3,5-dialkyl-4-hydroxyphenyl)methanes in which all of the alkyl groups contain from '3 to 8 carbon atoms, which alkyl groups are all branched on their respective alpha carbon atoms. These l,1-bis-(3,4-dialkyl-4-hydroxyphenyl)methanes are represented by the general formula wherein the groups designated by R, and R are alkyl groups containing from 3 to 8 carbon atoms and are further characterized being branched on their alpha carbon atoms.

A preferred embodiment of this invention relates to 1,1- bis-(3,5-di-tert-alkyl-4-hydroxyphenyl)methanes in which the tert-alkyl groups all contain from 4 to 8 carbon atoms. This preferred embodiment encompasses compounds which are particularly eifective antioxidants for oxygen-sensitive oils, such as lubricating oil, transformer oil, turbine oil, gear oil, greases containing the aforesaid type of oils, and the like.

A particularly preferred embodiment of this invention is 1,1 bis (3,5 di tert butyl 4 hydroxyphenyl) methane. This compound is a superlative antioxidant for a wide variety of oxygen-sensitive organic material, particularly oils and greases of the type described above.

Typical compounds of this invention include 1,1-bis- 3 ,5-di-isopropyl-4-hydroxyphenyl) methane; l, l-bis- 3,5 di sec butyl 4 hydroxyphenyl)methane; 1,1 bis- (3 isopropyl tert butyl 4 hydroxyphenyl)methane; 1,1 bis (3,5 di (2 octyl) 4 hydroxyphenyl) methane; -1,l bis (3 sec butyl 5 (2 hexyl) 4- hydroxyphenyl)methane;

1,1 bis (3 isopropyl 5- Patented July 5, 1960 2 (1,1,3,3-tetramethylbutyl)-4-hydroxyphenyl)methane, and the like.

The preferred class of compounds of this invention includes 1,1 bis (3 tert butyl 5 tert amyl 4- hydroxyphenyl)methane; 1,1 bis 3,5 di tert amyl? 4 hydroxyphenyl)methane; 1,1 bis (3,5 di (l,l,3,3- tetramethylbutyl)4 hydroXyphenyDmethane 1,1 bis- (3 tert butyl 5 (1,l,2,2 tetramethylpropyl) 4 hydroxyphenyl)methane, and the like.

As indicated above, 1,1-bis-(3,5-di-tert-butyl-4-hydroxyphenyl)methane is a particularly preferred embodiment of this invention.

The compounds of this invention are white crystalline solids and are soluble in various organic solvents and in gasolines, diesel fuels, hydrocarbon oils and the like. These compounds are further characterized by being relatively stable, non-hygroscopic, readily crystallizable materials.

The compounds of thisinvention are prepared by reacting formaldehyde with a 2,6-dialkylphenol in which both alkyl groups contain from 3 to 8 carbon atoms, both of said alkyl groups being branched on their alpha carbon atoms. In conducting this process according to a preferred embodiment, approximately two moles of the above-defined phenol are condensed with each mole of formaldehyde employed, using an alkali metal hydroxide such as sodium hydroxide as catalyst. This condensation reaction is conducted in a solvent consisting essentially of a monohydric alcohol containing from 1 to about '8 carbon atoms, preferably isopropyl alcohol. The reaction temperature is in the range of from about to about C. and preferably in the range of from about 50 to about 60 C.

The alkali metal hydroxide catalyst is used in catalytic quantities, namely, in amount equivalent to from about 0.5 to about 3 percent by weight of the phenol used in the reaction.

The following examples, wherein all parts and percentages are by weight, illustrate the compounds of this invention and the methods by which they are prepared.

EXAMPLE I In a reaction vessel equipped with stirring means, condensing means, thermometer and reagent introducing means was placed a solution of 6.6 parts of potassium hydroxide dissolved in 400 parts of isopropanol. To this stirred solution maintained under nitrogen atmosphere was added 206 parts of 2,6-di-tert-butyl phenol. At a temperature of 30 C. a total of 45.4 parts of '37 percent formalin solution was added dropwise. On heating to 60 C. a red color developed and a precipitation of crystalline product began. The mixture was stirred for 1 /2 hours at 60 C., cooled and the solid filtered off. The product was washed twice with 200 parts of isopropanol containing 10 parts of concentrated hydrochloric acid. After drying, the yield of product was 87 percent, melting point 154 to 155 C. The following chemical analysis showed the compound to be 1,l-bis-(3,5-di-tert-butyl- 4-hydroxyphenyl)methane: Calculated for C H O 82.2 percent carbon and 10.4 percent hydrogen. Found: 81.8 percent carbon and 10.5 percent hydrogen.

EXAMPLE II Using the reaction equipment of Example I, 178 parts of 2,6-diisopropyl phenol is reacted with 45.3 parts of 37 percent formalin solution in the presence of 6.6 parts of potassium hydroxide. 400 parts of isopropanol is used as the solvent. The reaction temperature is 50 C. A good yield of 1,*1-bis-(3,5-di-isopropyl-4-hydroxyphenyl)methane is obtained by hydrolyzing the reaction mixture and extracting the product with ethyl ether.

Evaporation of the ether solution gives an oil which slowly crystallizes.

EXAMPLE HI 1,1 bis (3,5 di (1,1,3,3 tetramethylbutyl) 4- hydroxyphenyl)methane is prepared as follows: In the reaction vessel of Example I are placed 318 parts of 2,6- di-(l,l,3,3-tetramethyl)-butyl)phenol, 6.6 parts of potassium hydroxide, 45.3 parts of 37 percent aqueous formalin solution and 400 parts of isopropanol. This mixture is stirred at 60 C. for 2 /2 hours. On cooling, the crystalline product which is formed is filtered 01f.

EXAMPLE IV In the reaction vessel of Example I are placed 492 parts of 2-isopropyl-6-tert-butylphenol, 4 parts of sodium hydroxide, 45.3 parts of aqueous formalin solution and 400 parts of isopropanol. This mixture is stirred at 65 C. for 3 hours. The mixture is then poured into excess cold water, extracted with ethyl ether, and the ether evaporated to give a residual oil which slowly crystallizes. This crystalline product is l,1-bis-(3-isopropyl-5-tertbutyl-4-hydroxyphenyl)methane.

EXAMPLE V In the reaction equipment described in Example I and using 400 parts of isopropanol as reaction solvent and 4 parts of sodium hydroxide as condensation catalyst, 234 parts of 2,6-di-tert-amyl phenol is reacted with 45.3 parts of 37 percent aqueous formalin solution. The temperature of this condensation reaction is 60 C. and the reaction time is 2 /2 hours. The solid material which precipitates is filtered off to give 1,l-bis-(3,5-di-tert amyl-4-hydroxyphenyl)methane.

EXAMPLE VI 1,1- bis (3 sec butyl 5 tert butyl 4 hydroxyphenyl)methane is prepared as follows: To the reaction vessel of the apparatus described in Example I are added 208 parts of 2-sec-butyl-6-tert-butyl phenol, 45.3 parts of 37 percent aqueous formalin solution, 4 parts of sodium hydroxide and 400 parts of n-propanol. The reactants are maintained at a temperature of 70 C. for a period of 3 hours. The reaction mixture is then poured into cold water, extracted with ethyl ether, from which is recovered the crystalline 1,1-bis-(3-sec-butyl- 5-tert-butyl-4-hydroxyphenyl)methane by evaporating off the ether.

EXAMPLE VII 310 parts of 2,6-di-(1,1,2,2-tetramethylpropyl)phenol is reacted with 45 .3 parts of 37 percent aqueous formalin solution in the reaction equipment rescribed in Example I. 500 parts of isopropanol is used as reaction solvent and 6.6 parts of potassium hydroxide is used as the condensation catalyst. The reaction temperature is 60 C. and the reaction time is 3 hours. 1,1-bis(3,5-di-(1,1,2,2- tetramethylpropyl)-4-hydroxyphenyl)methane is recovered by filtration of the reaction mixture from which this compound crystallizes.

To illustrate the useful properties of the novel compounds of this invention, recourse is had to the Polyveriform oxidation stability test as described in the paper entitled Factors Causing Lubricating Oil Deterioration in Engines" (Ind. & Eng. Chem., Anal. Ed., 17, 302 (1945)). See also A Bearing Corrosion Test for Lubricating Oils and Its Correlation with Engine Performance (Anal. Chem., 21, 737 (1949)). This test elfectively evaluates the performance of lubricating oil antioxidants. The test equipment procedure employed and correlations of the results with engine performance are discussed in the first paper above cited. By employing various compounds of this invention in oxygen-sensitive lubricating oil, effective inhibition of oxidative deterioration is achieved.

To demonstrate the preeminence of the particularly preferred compound of this invention1,1-bis-(3,5-ditert-butyl-4-hydroxyphenyl)methane-as an antioxidant for industrial lubricants, comparative tests were conducted using the method and apparatus essentially as described in the publication first above mentioned. One minor modification was that the steel sleeve and copper test piece described in this publication were omitted from the apparatus. In these tests an initially additive-free, VI. solvent-refined SAE-lO crankcase oil was used. The principal test conditions consisted of passing 70 liters of air per hour through the test oil for a total period of 20 hours while maintaining the oil at a temperature of 280 F. Oxidative deterioration of the oil was further promoted by employing as oxidation catalysts 0.05 percent by weight of ferric oxide (as ferric 2-ethyl hexoate) and 0.10 percent by weight of lead bromide, both of these amounts being based upon the weight of oil employed. A lubricating oil of this invention was then prepared by blending 1 percent by weight of l,1-bis-(3,5-ditert-butyl-4-hydroxyphenyl)methane with another portion of the above lubricating oil. This composition was then subjected to the above stringent oxidation test. To another portion of the same lubricating oil was added 1 percent by weight of 2,6-di-tert-butyl-4-methyl phenol, a commercial antioxidant which has found widespread use in lubricating oils. This sample was then subjected to the same test procedure. The results of these tests are shown in Table I.

,Table I.-Eflect of antioxidants on oxidation of lubricatl Saybolt Universal seconds.

By referring to the data presented in Table I, it is immediately apparent that 1,1-bis-(3,5-di-tert-butyl-4-hydroxyphenyl)methane exhibits a striking and unexpected potency in suppressing oxidative deterioration of lubricating oil. Furthermore, comparison of the results obtained in test 2 with those of test 3 shows that the compound of this invention is about eleven times as effective as a presently used commercial lubricating oil antioxidant. That this is particularly unexpected is still further apparent from the fact that 2,6-di-tert-butyl-4-methyl phenol bears a superficial resemblance insofar as chemical structure is concerned to the compound of this invention.

To still further demonstrate the preeminence of 1,1- bis (3,5 di tert-butyl 4 hydroxyphenyl)methane as an antioxidant for use in lubricating oil, another series of comparative tests was conducted. In this instance the test procedure used was essentially as described above with the exception that still more stringent test conditions were employed. These conditions were brought about by conducting the Polyveriform oxidation stability test at a temperature of 300 F. In these tests comparisons were made among a sample of the above-described, additive-free crankcase lubricating oil; a separate portion of this oil with which had been blended 1 percent by weight of 1,1-bis-(3,5-di-tert-butyl-4-hydroxyphenyl)- methane; and a third sample of this oil with which had been blended 2 percent by weight of 2,6-di-tert-butyl-4- .methylphenol. In Table II are shown the results of these tests.

Table II.-Efiect of antioxidants on oxidation of lubricat- 1 Saybolt Universal seconds.

It is clearly evident from the data shown in Table II that even under more stringent oxidizing conditions 1,1- bis-(3,5-di-tert-butyl-4-hydroxyphenyl)methane is four times as effective as 2,6-di-tert-butyl-4-methyl phenol. The clear-cut superiority of 1,l-bis-(3,5-di-tert-butyl-4-hy-' droxyphenyl)methane as compared with 2,6-di-tert-butyl- 4-methyl phenol is still further apparent by the fact that this substantial difference in effectiveness was brought about by the use of only one-half of the concentration of 1,lbis-(3,5-di-tert-butyl-4-hydroxyphenyl)methane in relation to the amount of 2,6-di-tert-butyl-4-methyl phenol used.

The compounds of this invention are particularly effective antioxidants for use in steam turbine oils. This is demonstrated by making use of the standard test procedure of the American Society for Testing Materials bearing ASTM designation D-943-54. According to this test procedure, 300 milliliters of a suitable test oil is placed in contact with 60 milliliters of water and the resulting oil-water system is maintained at a temperature of 95 C. while passing oxygen therethrough at a rate of 3 liters per hour. Oxidation is catalyzed by the use of iron and copper wire. Periodically measurements are made of the acid number of the test oil and failure of an antioxidant is indicated by an acid number in excess of 2.0. It is found that when the various compounds of this invention are added in small antioxidant quantities to steam turbine oils, substantial resistance against oxidative deterioration results.

The outstanding efficacy of the particularly preferred compound of this invention-1,l-bis-(3,5-di-tert-butyl-4- hydroxyphenyl)methaneas an inhibitor of oxidative deterioration of steam turbine oils was demonstrated by conducting a series of comparative tests according to the above ASTM test procedure. In these tests a 95 V1. solvent-refined SAE-IO hydrocarbon oil was used as the test oil. Steam turbine oil compositions of this invention were formulated by blending 0.7 and 1.0 percent by weight of 1,1-bis-(3,5di-tert butyl 4 hydroxyphenyl) methane with this test oil. For comparative purposes, identical concentrations of 2,6-di-tert-butyl-4-methyl phenol were blended with the same test oil. The results of these tests are shown in Table III.

Table [IL-Efiect of antioxidants on the oxidative de- Referring to the data of Table III, it is clearly apparent that 1,1-bis-(3,5-di-tert-butyl-4-hydroxyphenyl)methane is much more effective in inhibiting oxidative deterioration of steam turbine oil than is 2,6-di-tert-butyl-4-methyl phenol.

The compounds of this invention are very effective antioxidants for grease. The potency of the compounds of this invention in this respect is demonstrated by conducting the Norma Hoflman Grease Oxidation Stability Test, ASTM test procedure D-942-50. It is found that the presence of minor proportions of the compounds of this invention in conventional greases greatly inhibits oxidative deterioration. By way of example an initially antioxidantfree lithium base grease was modified to the extent that it contained 0.5 percent by weight of 1,1-bis-(3,5-di-tert- Jautyl-4-hydroxypheny1)methane and was subjected to the above oxidation stability test. It was found that the presence of 1,l-bis-(3,5-di-tert-butyl-4-hydroxpyhenyl) methane greatly retarded oxygen absorption by the grease. Thus, after maintaining this grease composition in the oxygen bomb for 376 hours under the standard test conditions, the oxygen bomb pressure had been reduced from p.s.i to 98 p.s.i. This represents a very small diminution of oxygen pressure in the light of the severe test conditions employed and is indicative of an extremely small amount of oxygen absorption.

The results described above are merely illustrative of the eifectiveness of the compounds of this invention when employed as antioxidants. The compounds of this invention effectively inhibit oxidation in industrial lubricants of the hydrocarbon type, such as lubricating oil, turbine oil, transformer oil, transmission fluids, glassannealing oil, gear and machine lubricants, hydraulic lubricants and other industrial oils, grease and the like. As pointed out above, the compounds of this invention as a class are efiective antioxidants. The preferred compounds of this invention-those which contain tert-alkyl groups containing from 4 to 8 carbon atomsare more elfective antioxidants than are the remainder of the compounds of this invention. As brought out by the experimental results described above, 1,l-bis-(3,5-di-tert-butyl- 4-hydroxyphenyl)methane is a superlative antioxidant.

The compounds of this invention are also very effective antioxidants for high molecular weight hydrocarbon polymers, such as polyethylene, polystyrene, polyisobutylene, polybutadiene, isobutylene-styrene copolymers, natural rubber, butyl rubber, GR-S rubber, GR-N rubber, methyl rubber, polybutene rubber, piperylene rubber, dimethyl butadiene rubber, and the like. A particular fearture of the compounds of this invention when employed for this purpose is that they are not only very effective in suppressing oxidation of the hydrocarbon polymers, but they possess the highly important and advantageous property of exhibiting non-staining characteristics even when employed in light-colored stocks, such as latex rubber. It has been found, for example, that 1,l-bis-(3,5-ditert-butyl-4-hydroxyphenyl)methane is superior to commercially used non-staining antioxidants particularly from the standpoint of its non-staining characteristics.

The compounds of this invention are also useful in protecting petroleum wax-paraffin wax and micro-crystalline waxagainst oxidative deterioration. The compounds of this invention also find use in the stabilization of edible fats and oils of animal or vegetable origin which tend to become rancid especially during long periods of storage because of oxidative deterioration. Typical representatives of these edible fats and oils are linseed oil, cod liver oil, castor oil, soybean oil, rapeseed oil, coconut oil, olive oil, palm oil, corn oil, sesame oil, peanut oil, babassu oil, butter, fat, lard, beef tallow, and the like. -,-'Ihe compounds of this invention may also be used as antioxidants for gasolines containing lead alkylantiknock agents, such as tetraethyllead; concentrated formulations of tetraalkyllead compounds, such as pure tetraethyllead or tetraethyllead admixed with organic halogen scavengers, oxygen-sensitive diesel fuels, domestic heating oils, bunker and residual fuel oils, asphalt, and other organic material normally susceptible of oxidative deterioration.

The amounts of the compounds of this invention em- 2. 1,1bis-(3,5di-tert-alkyl-4-hydroxyphenyl) methanes ployed in the materials to be stabilized are dependent both having the formula upon the nature of the material itself and the oxidative R1 R1 conditions to be encountered. Generally speaking, H amounts in the order of about 0.001 to about 2 percent 5 HO by weight of the material to be protected are satisfactory. i E

In some cases such as where the antioxidant is employed in an article normally subjected to severe oxidizing conditions, somewhat higher concentrations are useful.

The compounds of this invention are also useful as 10 germicides and disinfectants. In this general field of application the compounds of this invention can be used as wherein -R and R are tertiary alkyl groups containing from 4 to 8 carbon atoms.

3. 1,1,-bis-(3,5di-tert-butyl-4hydroxyphenyl) methane having the formula feed supplements to control coccidiosis in poultry. Whom" tert O4H The 2,6-dialkylphenols which are employed as starting H materials in the preparation of the compounds of this in- 5 H0 1 OH vention can be prepared by alkylating a phenol or an ap- I H propriate mono ortho alkyl phenol with an olefinic hydro- 4 tat-0J1 carbon in the presence of an aluminum phenoxide cata- References Cited in the fil f this patent g claim: 20 UNITED STATES PATENTS 1. 1,1,- bis -(3,5 dialkyl-4-hydroxyphenyl) methanes 2,506,486 Bender et May 1950 having the f l 2,515,908 Stevens et a]. July 18, 1950 2,538,355 Davis et a1. Jan. 16, 1951 R1 R; 2,647,102 Ambelang July 28, 1953 H 2 2,691,001 Cyphers et a1 Oct. 5, 1954 H0 gG-DH 2,734,924 Lambert Feb. 14, 195 6 I 1 2,735,872 Beaver et a1 Feb. 21, 1956 2,807,653 Filbey et a1 Sept. 24, 1957 wherein R and R are alkyl groups containing from 3 to 30 OTHER REFERENCES 8 carbon atoms and are branched on their respective al- Stifl on et a]; 1 m Amer. Chem. 800., vol. 67 1945), pha carbon atoms. pages 303-307 (5 pages).

UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 2,944,086 July 5, 1960 v Thomas H. Coirijfield et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below;

. Column 2, line 31, after "about", first occurrence,

insert 2O Signed and sealed this 4th day of July 1961.

* (SEAL) Attest:

SWIDER DAVID L. LADD ERA w Attestl rg Offlcer v C0mm1ss1oner of Patents Patent No. 2,944,086

Thomas H. Coffield et a1.

It is hereby certified t ent "requiring correctionend hat error corrected below'.

appears in the above numbered patthatthe said Letters Patent should read as Column 2, line 31, i I insert 2O after "about", first occurrence,

- (SEAL), Attest: ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents UNITED STATES PATENT oEETcE CER'HFMATWN UP @ORRECTWN Patent NOT 2,944,O86

Thomas H. Coffield et a1.

July 5, 1960 It is hereby cert ent requiring correction and that the sa ppears in the above numbered pat corrected below.

id Letters Patent should read as Column 2,

line 31, after "about" insert 20 --o first occurrence Signed and sealed this 4th day of July 1961.

(SEAL) Attest:

ERNEQTVZSWUDER DAVH)L.LADD Attesting Officer Commissioner of Patents 

1. 1,1,-BIS-(3,5 - DIALKYL-4-HYDROXYPHENYL) METHANES HAVING THE FORMULA 